AH-1 Cobra Pilot Posted September 17, 2018 Report Share Posted September 17, 2018 I just had my left brake go bad; I can press the brake all the way to the floor without effect. I checked the reservoir: OK. I bled the line: clean, good looking fluid came out at each actuation. I presume there is a problem with the seals in the brake actuator. Any advice? Quote Link to comment Share on other sites More sharing options...
1964-M20E Posted September 17, 2018 Report Share Posted September 17, 2018 Possibly the caliper piston is stuck? I'd pull the caliper off and replace the O-ring. A good cleaning and new O-ring should take care of things. Also if the pads are thin I'd replace them as well. One word of caution bleeding the system after this is time consuming mainly because the bleeder fitting is located on the bottom of the caliper. None of the things are difficult if you are working with your A&P. I changed both flexible brake lines in the wheel wells, brake pads and o-rings this past annual. Like I said bleeding the system was the most challenging and I used a pressure pot to force fluid into the system. The other option is possibly an air bubble in the left side that needs to be bled out. When bleeding the brake lines crack fittings along the way from the front to the rear loosening when the pressure is on and then tightening before the peddle is let to return to it's normal position. Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted September 17, 2018 Report Share Posted September 17, 2018 12 minutes ago, 1964-M20E said: Possibly the caliper piston is stuck? I'd pull the caliper off and replace the O-ring. A good cleaning and new O-ring should take care of things. Also if the pads are thin I'd replace them as well. One word of caution bleeding the system after this is time consuming mainly because the bleeder fitting is located on the bottom of the caliper. None of the things are difficult if you are working with your A&P. I changed both flexible brake lines in the wheel wells, brake pads and o-rings this past annual. Like I said bleeding the system was the most challenging and I used a pressure pot to force fluid into the system. The other option is possibly an air bubble in the left side that needs to be bled out. When bleeding the brake lines crack fittings along the way from the front to the rear loosening when the pressure is on and then tightening before the peddle is let to return to it's normal position. Wouldn't a stuck caliper piston result in being unable to depress the brake pedal? Quote Link to comment Share on other sites More sharing options...
1964-M20E Posted September 17, 2018 Report Share Posted September 17, 2018 Not when bleeding it and I do not think I have ever had a pedal in anything so solid that you could not depress it some, but he did say the pedal will go all the way to the floor. So I humbly reconsider my suggestions above and it could be the left master cylinder with a busted o-ring inside it. Just might be time to replace all the o-rings in the master cylinder. Quote Link to comment Share on other sites More sharing options...
bob865 Posted September 17, 2018 Report Share Posted September 17, 2018 I would assume that since you can press the brake pedal all the way down, you have a blown seal in that master cylinder. That would allow you to pump fluid when there is no back pressure, but once pressure is made, it pumps around the piston in the master cylinder instead of into the caliper. 1 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted September 17, 2018 Report Share Posted September 17, 2018 If the pads wear to the point that the o-ring in the wheel cylinder gets to the corroded part of the bore, it is possible that all the fluid suddenly dumped overboard. I've seen it happen. This makes a big puddle on the ground after you re-fill it and pump a few times. The older master cylinders would make pressure no matter what, the newer ones need to force two pistons together to make pressure. if there is the slightest amount of air in the master cylinder this won't work. You may have not bled it enough. 2 Quote Link to comment Share on other sites More sharing options...
Yetti Posted September 18, 2018 Report Share Posted September 18, 2018 3 o rings in the master cylinder or 4 depending on what you have. Pads are easy with the little anvil hand tool. Sounds like one of the o rings in the master cylinder. To bleed. I sucked fluid from the top, then used an oil can to pump up from the bottom. 40 pumps should do it if 20 does not. Quote Link to comment Share on other sites More sharing options...
Yetti Posted September 18, 2018 Report Share Posted September 18, 2018 https://www.amazon.com/GOLDENROD-737-Industrial-Oiler-Spout/dp/B00065UVZS/ref=sr_1_10?ie=UTF8&qid=1537237773&sr=8-10&keywords=oil+can+pump Quote Link to comment Share on other sites More sharing options...
MB65E Posted April 29, 2020 Report Share Posted April 29, 2020 Anyone have the part number for the thicker oring on the caliper for the older Cleveland brakes? The later -224 oring is too thin. Im away from my IPC. It’s at the hangar. I have 5 m/5988/1-224 orings available for the later pucks. thanks! -Matt Quote Link to comment Share on other sites More sharing options...
Andy95W Posted April 29, 2020 Report Share Posted April 29, 2020 This is for the 1965-1967. Looks like the cross reference is the MS28775-326, but please double check. Quote Link to comment Share on other sites More sharing options...
MB65E Posted April 29, 2020 Report Share Posted April 29, 2020 Thanks Andy!! -Matt Quote Link to comment Share on other sites More sharing options...
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